Congrats to COZX2 on the 100+ MPG fill!

[itjstagame]

Originally Posted by korax123

Ok i take back my previous statements. Congrats cause the On/Off switch is awesome and you can do that everyday. And it would be really cool if you had something to monitor how much battery life you have left so you know how long you can go until you can turn you alternator back on.

I would love to know how you hooked up the alternator to turn it off to if you could PM me that would be awesome.

Some cars have an voltmeter on the dash or in the gauge cluster. I guess a lot of new ones only have 'warning lights' that light when the battery is critically low (<8.5V?).

You can buy a cheap voltmeter gauge from any auto parts store, I bet it's $10-20. You'll easily be able to see when charging (14V or so) and when not charging (12.5V or so) and if you have alternator off you can watch the charge slowly drop down, I'd say typically below 8.5-9V is when you're too low, most ECUs or ignitors will start having problems. I know my old audi will run the injectors and sparkplugs to 5V but below 8V it will not time the spark as correctly and the tachometer just jumps all over uselessly. Of course that's because I needed a new alternator, yeah for stuff breaking.

Originally Posted by 88HF

my injectors all have black/red wires and then the colored wires. According to the manual, the red/black wires are the signal wires(+), and the colored wires are for ground (-). I don't know why this is the case, but I've done some work tracking the wires around and it seems to be as the manual states. I just bought a couple toggles and some 18 gauge stranded wire.

Some ECUs will ground the negative to control the injector instead of the positive. That is they'd all have common positive connections all the time and the ECU will ground them when it wants them to fire. I'm pretty sure this is how my Megasquirt works (can you tell it's been a long time since I've read it).

Anyway I would say, whichever wire you decide to cut, after you cut it, test it with an ohmmeter. That is, hook your test leads, one to the negative side of the battery and another to the piece of wire heading away from the injector (not the one heading to the injector). If this is trully the ground wire and if it is truly grounded all the time (ie. ECU uses positive wire to fire) then you should have a circuit.


CO! Can you point us to a thread or make a new one where you outline what exactly you did for those gauges? Are they simple air pressure gauges like an airplane would use? I assume you don't use something like a vacuum or boost gauge because they wouldn't be precise enough. About what maximum ranges are we talking about with the negative draft pressures, a couple 2-5psi off of 14.7? I'm just trying to think what gauges would have graduations at .5psi or less.

Also do you just tape (duct tape) your tubes to whatever surface you want to read, do you worry about which way the openning of the tube is facing at all? I think this sounds like the best way to decide on aero mods, it's very interesting you found it best without a full belly pan, etc, I certainly don't want to do too much to my car and make it worse but considering the vehicles I have they can't get much worse .

Also congrats! I look forward to challenging you in the future, though I may need a more aerodynamic car for that, if I can get 100% over EPA on either car I'll consider it a success.


Lastly (boy this is a long post), applying the few techniques I've read in the fiances car I did get some gains but I was still boggled at how one could get a higher MPG then the cruising MPG on level ground (since that seems like the best the engine can do). How do you get 50-60MPG on your return trip? Even a minor grade in her car drops me to 10-15MPG no matter how slow I try to accelerate. Accelerating harder (like WOT) makes the tranny drop a gear and I go to 6-8MPG. So I guess I'm curious what the best way to tackle a hill is, highest gear possible and WOT? Or 60-80% (to stay below the ignore open loop and shoot for 12.5 AFR mode)?

[itjstagame]

Originally Posted by omgwtfbyobbq

Depends on the grade and mods. I'm guessing that CO ZX2 is setup so that he can engine off coast in gear, or N. While EOC'ing in gear is wasteful compared to out of it in terms of time, it's still using no fuel, so whatever the peak mileage is it can still be attained, just at a proportionally lower speed than it could be attained using P&G. In fact, P&G generally bites compared to long enough mountains because by using it, the car can't warm up totally and ends up running through the enriched cycle/inefficient portion of the BSFC map a significant amount of time. In fact, in all my experience, climbing mountains with steepish grades in EFI manuals generally helps because efficiency is way greater than in the flats, something like 50-100% better, and when I'm going down the other side in gear, I'm using no fuel as long as I'm above the idle fuel cut.

Oh, I just wanted to post one more comment. About this topic it seems to make sense to me, P&G can be thought of climbing a nonexistant mountain and then coasting down it. Granted it seems off from a power stand point, especially since your drive train is anything but lossless so you'll never get back all you put in. Engines must just be THAT much more efficient when accelerating versus maintiaining speed. Considering I can accelerate at an ok pace while maintaining my same MPG as my cruise MPG from 50-70MPG I'd say cruising is akin to me wasting energy.

[MetroMPG]

Originally Posted by itjstagame

I'd say typically below 8.5-9V is when you're too low

From what I've learned about EV's, you want to avoid drawing a lead acid 12v battery down below 10.5v under load. Below 10.5 risks cell damage (cooking the battery).

And of course the deeper a battery is discharged on a regular basis, the faster it wears out (lost capacity).

[CO ZX2]

[quote=itjstagame;65805]
CO! Can you point us to a thread or make a new one where you outline what exactly you did for those gauges? Are they simple air pressure gauges like an airplane would use? I assume you don't use something like a vacuum or boost gauge because they wouldn't be precise enough. About what maximum ranges are we talking about with the negative draft pressures, a couple 2-5psi off of 14.7? I'm just trying to think what gauges would have graduations at .5psi or less.

The following comments were excerped from recent PMs.
CO ZX2: The pressure/flow gauges are Dwyer. My gauges scale in inches of water(WC), much more sensitive than psi. I tape the tubing crosswise of the airflow. I sometimes use 6 gauges at once to cut down on test time, fewer work fine, just take longer.

[quote=itjstagame]Thanks again, last one (then I'll stop, promise), would you get 0-.25in of water or 0-1 in of water. I want to get the highest precision one I can find, so just curious which ranges of pressures you have seen.

CO ZX2: I am at 10,000 ft. altititude and my readings are not what would be expected at lower altitudes, so readings I get here may not be of much use to you.

It is not too hard to look at one gauge at 60, you only have to read it there, it is calibrated to 0 at rest.

I have one gauge that records but uses 110V. It is also big and heavy. Seemed like a good idea but too much trouble. If you are going to get one gauge you should probably get a 0-10-0. Has the capability to read high and low pressures without switching the tubing ports. You should probably have a 0-3 to use at the rear. But you may require 0-5.

0-.25 would not do you much good, especially at first, not enough scale. A 0-1 is a real nice gauge to have but will not cover all your needs. I just took my best guesses and ended up with more gauges than I will ever use here.

I could spare a 0-10-0. Or 0-10 for less money, just as good, just have to plug the tubing into low or high port. And I have extra 0-.5, great for refining when you get that far.

[1993CivicVX]

Wow, pretty impressive mods and MPG achievement! I find this thread rather inspiring. This is the kind of thing that needs to get publicity. At the very least, CO should get the local media or newspaper to cover his project and the MPG he has attained. Really, it should be a national news story. Surely others agree with me? It would be great as an inspirer to other people at what sort of FE from an ordinary automobile is possible, if not just an interesting and amazing story about an ordinary car getting extraordinary FE. Also could submit this project to some car mags. Maybe get on Jay Leno's show. I bet he'd be really interested to have you on his show to learn a bit about how you modded it etc. (he's a car guy) Anyway, I think publicity is a good thing when it comes to people eeking as much gas from their vehicles as possible.

I find the bit about vacuum turbulence at the rear of the car very interesting. I will have to do some research into reducing it on the VX. I do believe the Civic VX Hatchback has the same drag coefficient of 31 as CO's car stock, so CO's car gives me an idea of how much I could possibly further reduce my cD. CO, what are your tires rated for PSI?

Well done!

P.S.

I think a very interesting and easy test would be to do a tank driving "normal." Just to get an idea of how much the mods are doing without the variable of driving technique. Maybe lend your car to someone who doesn't know the first thing about FE and economical driving techniques and see what kind of gas mileage they get. Of course, some of your mods wouldn't get used in this case, like the alternator on/off switch. But still would be interesting! Or maybe have your car sent to the EPA people to see what it's EPA numbers are now. hehe. Okay, I'm getting way too carried away with this....

[1993CivicVX]

About P&G on hills verses flats. I think one advantage P&G has with hills over flats is you can maintain a constant speed going up the hill so as not to accrue a lot of wind drag and RR by going faster to make the glide longer. So instead of wind and rolling resistance being the major factor with a pulse going up a hill, it's the hill. And when going down the other side of the hill, wind resistance again is less an issue if the hill isn't too steep. You can glide for miles down a gradual hill at 40mph--with lower wind and rolling resistance but a very long glide. So this situation might be better than accelerating to 50mph and then coasting down to 35, where wind and rolling resistance is higher. Not sure how this applies to big mountains. If the hill is steep going up, but gradual going down--that is an ideal situation. A long gradual hill going up and a steep hill going down is very bad. I have to assume the hills CO is driving on are not like this? Maybe you could describe your daily route in detail CO? Would be rather interested to know.

[itjstagame]

I too would be curious to see what happens if someone else drives his car.

The reason his car wasn't on top is because his 90 day average is 0MPG so it must be using his lifetime average. It's right here http://www.gassavers.org/garage/view/239

[jBubb]

Congrats!

[Mighty Mira]

Just found this thread, and ran some numbers on my simulator for his car. I'd estimate that his drag coefficient is better than mine, and CdA would be similar. Maybe better.

He's lucky to be at 10,000 feet with primarily hilly, highway driving. Not only does he get something like 67&#37; of the drag that he'd get at my altitude (basically sea level), he also gets to operate his engine at higher BSFC most of the time. Although probably not really applicable if everything is in pulse all the time.

The car is also prime for aero modding - that area at the rear of the car is tiny. If you take care of the rest of the aero ugliness inherent in the car - underpan, skirts, grille, I'm not at all surprised that he's generating that sort of FE with P&G driving.

Note that for someone new to P&G, the hills force them to accelerate at better BSFC than the scanguage would tell them to. With a more experienced driver, the hills also help because you minimize the times you are expending energy in bump starting the car, getting it up to revs, heating up the clutch, etc.

So basically, surprising at first but not when you do the math. At my altitude and on my commute (combined cycle, but leaning towards city), he'd be getting about 10-15% worse FE. His heavier car sees to that with more wasted KE in stopping.

Congratulations are in order, so well done! But this also goes to show that in order to understand how to improve FE, more is necessary than just thinking of things in terms of a rudimentary X mpg improvement. If you are improving CdA, you need to measure that. You also have to take into account temperature and altitude into account, the type of commute, driving techniques, etc. Primarily directed at those who would doubt that this is possible.